Area Forecast Discussion
Issued by NWS Anchorage, AK

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FXAK68 PAFC 300011
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
411 PM AKDT FRI APR 29 2016

.ANALYSIS AND UPPER LEVELS...
WEATHER RADAR DEPICTS WIDESPREAD SCATTERED TO NUMEROUS SHOWER
COVERAGE ALONG COASTAL LOCATIONS...ESPECIALLY SOUTH AND EAST-
FACING SLOPES OF THE COASTAL MOUNTAIN RANGES. GUSTY SOUTHEAST
WINDS CONTINUE THROUGH THE SOUTHEAST GAPS OF THE MOUNTAIN
RANGES...IMPACTING AREAS SUCH AS ANCHORAGE PALMER GLENNALLEN AND
BRISTOL BAY. OTHERWISE...CONDITIONS ARE RELATIVELY BENIGN ACROSS
MUCH OF THE SOUTHCENTRAL AND SOUTHWEST PARTS OF THE STATE.

A PAIR OF MID-LEVEL LOWS...ONE A REMNANT UPPER LOW NEAR THE
SOUTHERN AKPEN AND THE OTHER A PART OF A FAIRLY STRONG NORTH
PACIFIC LOW CENTERED ABOUT 625 NM SOUTH-SOUTHWEST OF SITKINAK
ISLAND...ARE CURRENTLY BEGINNING THE PROCESS OF CONSOLIDATING OVER
THE NORTH PACIFIC SOUTH OF THE AKPEN. THE LARGE CIRCULATION
ENCOMPASSES MOST OF THE ANCHORAGE AREA OF RESPONSIBILITY...WITH
THE EXCEPTION OF A MID-LEVEL RIDGE CURRENTLY MOVING INTO THE FAR
SOUTHWEST BERING AND WESTERN ALEUTIANS.

THE SURFACE FEATURES OF NOTE ARE A FAIRLY ROBUST GALE-FORCE FRONT
WHICH EXTENDS WELL AHEAD OF THE SURFACE LOW AND IS HEADING TOWARD
ENTERING THE SOUTHERN GULF THIS EVENING.

&&

.MODEL DISCUSSION...
MODELS ARE IN GOOD AGREEMENT THROUGH SUNDAY AFTERNOON...RESULTING
IN A FAIRLY HIGH CONFIDENCE FORECAST FOR MOST LOCATIONS.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 AND 2)...
A WARM FRONT CURRENTLY LOCATED OVER THE NORTH PACIFIC WILL
QUICKLY MOVE INTO THE GULF OF ALASKA TONIGHT AND MOVE TO THE
NORTHERN GULF COAST BY SATURDAY MORNING. THE FRONT WILL BE
FAVORABLY ORIENTED WITH THE COASTAL RANGE WHICH WILL ALLOW A STORM
FORCE BARRIER JET TO DEVELOP RIGHT ALONG THE GULF COAST. FOR THE
MOST PART...MOST COASTAL WATERS AND OFFSHORE ZONES WILL SEE GALE
FORCE WINDS ASSOCIATED WITH THIS QUICK MOVING FRONT BUT WILL BE
SHORT LIVED AS THE FRONT IS EXPECTED TO WEAKEN RAPIDLY BY THE TIME
IT MAKES IT TO THE GULF COAST. RAINFALL ASSOCIATED WITH THIS FRONT
COULD BE HEAVY AT TIMES ALONG THE IMMEDIATE GULF COAST AS RAIN
UPSLOPES ALONG THE COASTAL RANGE. A FEW SPRINKLES COULD MAKE IT
INLAND LATE SATURDAY AND SUNDAY BUT DOWNSLOPING WINDS SHOULD
MITIGATE THE AMOUNT OF RAINFALL THAT IS ABLE TO MAKE IT INLAND.

SPEAKING OF WINDS...THE COMBINATION OF A COASTAL RIDGE AND THE
APPROACHING FRONTAL BOUNDARY WILL CONTINUE A COMPACT GRADIENT
ORIENTED FROM EAST TO WEST. THIS WILL ALLOW THE GUSTY WINDS THAT
HAVE BEEN OBSERVED THROUGH THE PAST WEAK FROM EAST TO WEST
ORIENTED GAPS TO CONTINUE THROUGH THE WEEKEND. GUSTY WINDS IN THE
ANCHORAGE BOWL WILL COME TO AN END TONIGHT AS THE BOUNDARY LAYER
STABILIZES AFTER SUNSET.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 AND 2)...
THE PATTERN WILL REMAIN MUCH THE SAME THROUGH THE WEEKEND. BROAD
CYCLONIC FLOW...CENTERED AROUND A LOW APPROACHING KODIAK...WILL
DOMINATE. THIS WILL KEEP MOIST AND MILD SOUTHEAST FLOW PUSHING
OVER THE ALASKA AND ALEUTIAN RANGES. THE NET EFFECT AT THE SURFACE
WILL BE CONTINUED WELL ABOVE NORMAL TEMPERATURES AND A CHANCE OF
RAIN THROUGHOUT THE AREA. BY SUNDAY...THERE SHOULD BE ENOUGH EARLY
SUN TO HELP TO BUILD SOME BETTER INSTABILITY ACROSS THE KUSKOKWIM
VALLEY. AS YET ANOTHER WEAK PIECE OF ENERGY ROTATES AROUND THE
LOW...THIS COULD BE JUST ENOUGH TO HELP TRIGGER A FEW
THUNDERSTORMS. SO WE HAVE INTRODUCED SOME ISOLATED THUNDERSTORMS
ACROSS THE NORTHERN HALF OF BRISTOL BAY AND MOST OF THE KUSKOKWIM
VALLEY. CONFIDENCE IS MARGINAL IN THIS EVENT...BUT A STRIKE OR TWO
IS NOT OUT OF THE QUESTION.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 AND 2)...
AS THE PARENT NORTH PACIFIC LOW PULLS OFF TOWARDS KODIAK SAT...IT
WILL LEAVE WEAK NORTHERLY FLOW AND WIDESPREAD MARINE FOG/STRATUS
IN ITS WAKE. WHILE IT LOOKS LIKE MOST OF THIS WILL HOLD AS LOW
STRATUS...IT COULD DROP VISIBILITIES AT THE SURFACE FROM TIME TO
TIME. BY LATE SAT INTO SUN...A NEW WARM OCCLUSION WILL APPROACH
THE WESTERN ALEUTIANS. THIS WILL BRING MINIMUM GALE FORCE WINDS
TO THE EXTREME WESTERN MARINE AREAS WITH MORE RAIN SPREADING FROM
THE WESTERN TO THE CENTRAL ALEUTIANS ON SUN.

&&

.LONG TERM FORECAST (DAYS 3 THROUGH 7...MON THROUGH FRI)...
NOT A LOT OF CHANGE EXPECTED IN THE LONG TERM. ONE UPPER-LEVEL
WILL SLOWLY FILL AND WEAKEN OVER THE GULF EARLY IN THE WEEK.
ANOTHER NEW LOW WILL DEVELOP OVER THE CENTRAL ALEUTIANS AND TRACK
SLOWLY EAST. THIS WILL ALLOW A RIDGE TO BUILD IN FRONT OF THE
SECOND LOW OVER SOUTHERN ALASKA ON TUE AND WED. THIS WILL BRING A
BRIEF BREAK TO THE CONTINUOUS SOUTHEAST FLOW AND ASSOCIATED
FRONTS IMPACTING THE GULF COAST. IT COULD ALSO BRING THE BEST
CHANCE FOR SOME WIDESPREAD SUNSHINE ACROSS MUCH OF THE SOUTHERN
MAINLAND. BY THE MIDDLE OF THE WEEK THOUGH...MODELS BEGIN TO
DIVERGE ON TWO SIGNIFICANT ISSUES. THE FIRST IS HOW MUCH ENERGY
PUSHES INTO THE RIDGE OVER SE ALASKA AND THE SECOND IS WHAT
STRUCTURE THE LOW APPROACHING FROM THE ALEUTIANS TAKES ON. IF
ENOUGH ENERGY PUSHES INTO THE RIDGE...IT WILL SIMPLY GIVE WAY AND
MOVE EAST. BUT IF SOME WARM AIR ADVECTED INTO IT CAUSING IT TO
BUILD...THE ENERGY MIGHT JUST RIDE UP ITS WESTERN FLANK STRAIGHT
INTO SOUTHERN AK. THE STRUCTURE OF THE LOW VARIES FROM THE GFS
DEPICTION OF A VERTICALLY STACKED LOW TRACKING SLOWLY EAST TO THE
EC SHOWING IT MORE PROGRESSIVE WITH A NEW TRIPLE-POINT LOW FORMING
OVER THE SOUTHERN GULF BY NEXT WEEKEND. THIS FORECAST PACKAGE
LEANED TOWARDS KEEPING THE HIGHEST POPS ALONG COASTAL LOCATIONS AT
THIS TIME. TEMPERATURES LOOK TO REMAINS NORMAL TO ABOVE NORMAL AS
WE START MAY. THIS COULD LEAD TO SOME WEAK INSTABILITY...SO WE
WILL BE WATCHING CHANCES FOR CONVECTION.

&&


.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...STORM WARNING 119 120 130 131.
 GALE WARNING 125 132 136 137 138 139 150.

&&

$$

SYNOPSIS AND MODEL DISCUSSION...CC
SOUTHCENTRAL ALASKA...MC
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...MO
LONG TERM...MO



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